<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>波点背景</title>
    <style>
      .dot {
        width: 100%;
        height: 500px;
        background-image: radial-gradient(circle at 5px 5px, #3409f1 2px, transparent 3px);
        background-color: #fff;
        background-size: 30px 30px;
      }
    </style>
  </head>
  <body>
    <div class="dot"></div>
  </body>
</html>
